1. Field of the Invention
The present invention relates to a drive apparatus, a vehicle having the drive apparatus mounted thereon, and a method for controlling the drive apparatus. More particularly, the present invention relates to a technique of discharging charges remaining in a capacitor in the drive apparatus.
2. Description of the Background Art
As an environmentally-friendly vehicle, attention has been recently focused on an electric powered vehicle that has a power storage device (such as, for example, a secondary battery or a capacitor) mounted thereon and runs using drive force generated from electric power stored in the power storage device. This electric powered vehicle includes, for example, an electric vehicle, a hybrid vehicle, a fuel cell vehicle and the like.
This electric powered vehicle may include a motor generator for receiving electric power from the power storage device and generating drive force for running at the time of startup or acceleration, and generating electric power by regenerative braking and storing electrical energy in the power storage device at the time of braking. In order to control the motor generator depending on the running state as described above, a power conversion device converting electric power with a converter and an inverter is mounted on the electric powered vehicle.
This power conversion device includes a large-capacitance smoothing capacitor to stabilize supplied DC electric power. During operation of the power conversion device, charges corresponding to an applied voltage are stored in the smoothing capacitor.
These charges stored in the smoothing capacitor must be discharged quickly when a vehicle crash occurs, for example.
Japanese Patent Laying-Open No. 2004-201439 discloses such a configuration that in a hybrid vehicle or an electric vehicle, charges remaining in a capacitor included in a voltage conversion system are charged back to a DC power supply when driving of a motor stops, and the charges remaining in the capacitor are discharged with a converter by repeating a boosting operation and a step-down operation of the converter included in the voltage conversion system when a voltage across the capacitor becomes equal to or lower than a voltage of the DC power supply and chargeback becomes impossible.